Electronic device packages come in many forms. Some contain elements such as inductors, capacitors, and integrated circuit (IC) chips. There are electronic device packages that integrate a complete electronic system, often referred to as a system-in-a-package (SIP). A SIP usually has a dielectric substrate, which is a single layered or multi-layered slab of dielectric material with a conductive wiring circuit built in it. Some substrates may contain IC chips connected by the conductive wiring circuit with through-holes between the multiple layers.
Traditionally, in a SIP that has a substrate, one side of the substrate (the bottom surface) is designed for connecting the package to the outside world, for example a mother board, and the other side (the top surface) is designed for the placement of various circuit elements. The circuit elements are connected to form the electronic system by the conductive wiring circuit in the substrate or with additional metal wires. One example of a SIP is a switching power converter.
The modern switching power converter comprises at least an integrated IC with both power and controller functions, an input capacitor, an output capacitor, and an inductor. The package has an input lead (VIN), an output lead (VOUT), a ground lead (GND), plus other leads for functions such as enabling, mode selection and output voltage sensing. The input capacitor is connected to the VIN lead, GND, and the controller chip; and the output capacitor is connected to VOUT lead, GND and the controller chip. This power system enables a precise, regulated output voltage starting from a poorly controlled input voltage as power is rapidly added and subtracted from the inductor. The main advantage of this arrangement is highly efficient electrical power conversion in a small format. A disadvantage is the generation of electromagnetic interference and noise due to high frequency switching. The capacitors provide low-pass filtering.
In a traditional build-up, the controller chip, the inductor, and the capacitors are all placed side-by-side on the substrate. In a more advanced SIP, the controller chip may be embedded in the substrate so that only the inductor and the capacitors are on the surface of the substrate. One embeddable package is known as PICOSTAR by Texas Instruments Incorporated which allows embedding of components such as semiconductor chips inside the printed circuit board (PCB) in order to minimize the board space.